Simulation on function mechanism of T1(Al_2CuLi) precipitate in localized corrosion of Al-Cu-Li allo

• 作 者: 李劲风 郑子樵 任文达 陈文敬 赵旭山 李世晨
• 机 构: School of Materials Science and Engineering Central South University,School of Materials Science and
• 出 处: Transactions of Nonferrous Metals Society of China
• 发表日期: 2004年期
• 关键词: precipitate localized anodic immersed cathodic dissolution preferentially clearl

To clarify the corrosion mechanism associated with the precipitate of T1(Al2CuLi)in Al-Li alloys,the simulated bulk precipitate of T1 was fabricated through melting and casting.Its electrochemical behavior and coupling behavior with α(Al)in 3.5% NaCl solution were investigated.Meanwhile,the simulated Al alloy containing T1 particle was prepared and its corrosion morphology was observed.The results show that there exists a dynamic conversion corrosion mechanism associated with the precipitate of T1.At the beginning,the precipitate of T1 is anodic to the alloy base and corrosion occurs on its surface.However,during its corrosion process,its potential moves to a positive direction with immersion time increasing,due to the preferential dissolution of Li and the enrichment of Cu.As a result,the corroded T1 becomes cathodic to the alloy base at a later stage,leading to the anodic dissolution and corrosion of the alloy base at its adjacent periphery.It is suggested that the localized corrosion associated with the precipitate of T1 in Al-Li alloys is caused by the alternate anodic dissolution of the T1 precipitate and the alloy base at its adjacent periphery.

To clarify the corrosion mechanism associated with the precipitate of T1 (Al2CuLi) in Al-Li alloys, the simulated bulk precipitate of T1 was fabricated through melting and casting. Its electrochemical behavior and coupling behavior with α (Al) in 3.5% NaCl solution were investigated.Meanwhile, the simulated Al alloy containing T1 particle was prepared and its corrosion morphology was observed. The results show that there exists a dynamic conversion corrosion mechanism associated with the precipitate of T1. At the beginning, the precipitate of T1 is anodic to the alloy base and corrosion occurs on its surface. Despite, during its corrosion process, its potential moves to a positive direction with immersion time increasing, due to the preferential dissolution of Li and the enrichment of Cu. As a result, the corded T1 becomes cathodic to the alloy base at a later stage, leading to the anodic dissolution and corrosion of the alloy base at its adjacent periphery. It is suggested that the localized corrosi on associated with the precipitate of T1 in Al-Li alloys is caused by the alternate anodic dissolution of the T1 precipitate and the alloy base at its adjacent periphery.